An indium tin oxide (ITO) film is an indispensible component of an electrode in a liquid crystal display or a transparent metal film for electrostatic shielding. The ITO film is of a very small thickness and has high visible-light transmittance, so it is difficult for human's eyes to determine whether the ITO film exists or not.
In an existing detection method, whether the ITO film exists or not is mainly detected by testing an area resistance of a substrate. However, it takes a long period of time for a traditional device to test the area resistance of the substrate, and an area to be detected is relatively small, so it is impossible to perform the detection rapidly.